/// <summary>
/// Gets a rotation matrix that, when multiplied by a column matrix representing a
/// position vector in patient coordinates, will rotate the position vector
/// into a coordinate system matching that of the image plane.
/// </summary>
/// <returns>The rotation matrix, or null if the <see cref="Frame"/>'s position information is invalid.</returns>
private Matrix3D GetRotationMatrix()
{
if (_rotationMatrix == null)
{
if (ImageOrientationPatient.IsNull)
return null;
var normal = GetNormalVector();
if (normal == null || normal.IsNull)
return null;
_rotationMatrix = new Matrix3D();
_rotationMatrix.SetRow(0, (float) ImageOrientationPatient.RowX, (float) ImageOrientationPatient.RowY, (float) ImageOrientationPatient.RowZ);
_rotationMatrix.SetRow(1, (float) ImageOrientationPatient.ColumnX, (float) ImageOrientationPatient.ColumnY, (float) ImageOrientationPatient.ColumnZ);
_rotationMatrix.SetRow(2, normal);
}
return _rotationMatrix;
}
private static void Rotate(Matrix3D transform, float angle, float x, float y, float z)
{
const double rads = Math.PI/180;
var c0 = Math.Cos(rads*angle);
var c1 = 1 - c0;
var xc1 = x*c1;
var yc1 = y*c1;
var zc1 = z*c1;
var s = Math.Sin(rads*angle);
var xs = x*s;
var ys = y*s;
var zs = z*s;
var r = new Matrix3D(new[,]
{
{(float) (x*xc1 + c0), (float) (x*yc1 - zs), (float) (x*zc1 + ys)},
{(float) (y*xc1 + zs), (float) (y*yc1 + c0), (float) (y*zc1 - xs)},
{(float) (z*xc1 - ys), (float) (z*yc1 + xs), (float) (z*zc1 + c0)}
});
var m = r*transform;
transform.SetRow(0, m[0, 0], m[0, 1], m[0, 2]);
transform.SetRow(1, m[1, 0], m[1, 1], m[1, 2]);
transform.SetRow(2, m[2, 0], m[2, 1], m[2, 2]);
}